Effect of Temperature on the Hydration of White Portland Cement–Metakaolin Blends Studied by ²⁹Si and ²⁷Al MAS NMR

TY - GEN

T1 - Effect of Temperature on the Hydration of White Portland Cement–Metakaolin Blends Studied by 29Si and 27Al MAS NMR

AU - Dai, Zhuo

AU - Skibsted, Jørgen

N1 - Conference code: 3

PY - 2020/1

Y1 - 2020/1

N2 - Metakaolin can be considered as a model compound foran aluminosilicate-rich supplementary cementitious material (SCM) because of its composition and highly pozzolanic properties. This work presents a systematic investigation of the hydration of white Portland cement (wPc)–metakaolin (MK) blends cured at different temperatures by 29Si and 27Al MAS NMR with the main focus on the structure and composition of the C-(A)-S-H phase. White Portland cement–MK paste samples with wPc replacement levels of 0, 10, 20, and 30 wt% have been prepared and hydrated for 1–8 weeks at five different temperatures (5, 20, 40, 60, and 80 °C). Information on the degree of reaction for alite, belite, and MK is derived from the 29Si NMR spectra and shows that the hydration of the wPc–MK blends is accelerated with increasing temperature except for the blend with the highest MK level (30 wt%). The AlIV/Si ratio of the C-(A)-S-H phase is found to be independent on the hydration time but increases slightly with curing temperature. On the other hand, a significant increase in the average aluminosilicate chain lengths is observed for blends with increasing temperature, reflecting a decrease in the Ca/Si ratio for the C-(A)-S-H phase. Strätlingite is present in the wPc–MK blends at 20 °C and the fraction of this phase decreases with increasing curing temperature.

AB - Metakaolin can be considered as a model compound foran aluminosilicate-rich supplementary cementitious material (SCM) because of its composition and highly pozzolanic properties. This work presents a systematic investigation of the hydration of white Portland cement (wPc)–metakaolin (MK) blends cured at different temperatures by 29Si and 27Al MAS NMR with the main focus on the structure and composition of the C-(A)-S-H phase. White Portland cement–MK paste samples with wPc replacement levels of 0, 10, 20, and 30 wt% have been prepared and hydrated for 1–8 weeks at five different temperatures (5, 20, 40, 60, and 80 °C). Information on the degree of reaction for alite, belite, and MK is derived from the 29Si NMR spectra and shows that the hydration of the wPc–MK blends is accelerated with increasing temperature except for the blend with the highest MK level (30 wt%). The AlIV/Si ratio of the C-(A)-S-H phase is found to be independent on the hydration time but increases slightly with curing temperature. On the other hand, a significant increase in the average aluminosilicate chain lengths is observed for blends with increasing temperature, reflecting a decrease in the Ca/Si ratio for the C-(A)-S-H phase. Strätlingite is present in the wPc–MK blends at 20 °C and the fraction of this phase decreases with increasing curing temperature.

KW - C-(A)-S-H phase

KW - Metakaolin

KW - Temperature

UR - http://www.scopus.com/inward/record.url?scp=85090016726&partnerID=8YFLogxK

U2 - 10.1007/978-981-15-2806-4_33

DO - 10.1007/978-981-15-2806-4_33

M3 - Article in proceedings

AN - SCOPUS:85090016726

SN - 978-981-15-2805-7

T3 - RILEM Bookseries

SP - 283

EP - 292

BT - Calcined Clays for Sustainable Concrete

A2 - Bishnoi, Shashank

PB - Springer

CY - Singapore

T2 - 3rd International Conference on Calcined Clays for Sustainable Concrete

Y2 - 15 October 2019 through 19 October 2019

ER -